Chaeles b



(No Model.)

0. E. SGRIBNER.

ANNUNGIATOR CIRCUIT FOR TELEPHONE EXCHANGES.

No. 245,404. Patented Aug. 9,1881.

NY PETERS. PhoIwLIlhognpher, Wusmnglon. n. c

Earth STATES ATENT rrrcn.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNCR TO WESTERN ELECTRICMANUFACTURING COMPANY, OF SAME PLACE.

ANNUNCIATOR-CIRCUIT FOR TELEPHONE-EXCHANGES.

SPECIFICATION forming part of Letters Patent No. 245,404, dated August9, 1881.

Application filed June 20, 1881. (No model.)

To all whom it may concern Be it known that I, CHARLES E. SCRIBNER, ofChicago, Illinois, have discovered a certain new and useful Improvementin Annunciator- Circuits for Telephone-Exchanges, of which the followingis a full, clear, concise, and exact description.

My improvement consists in so connecting the individual telephone-lineswith annunciators that any subscriber may automatically send a currentfrom the battery at the central office through the annunciator in. hisline, and so that when any two connected subscribers are throughspeaking the one who first hangs up his telephone will by that actautomatically close said battery to a circuit including the annunciatorsin their connected lines.

In the drawing 1 have shown five terminal stations, with thesubscribersindividual lines connected at their outer ends to a commonline in the usual manner. Each of these lines passes through itsannunciator and switch at the central office and to a common line, inwhich is placed a battery, as shown. When the telephone is taken fromthe switch at either station the telephone-line of that station is cutotf from the common outer line and connected to ground. The circuit ofthe battery at the central oftlce is thus completed through thetelephone-line .that is thus grounded, and the annunciator of said lineis thrown down. The work of connecting the calling subscriber withlistening operator and with the subscriber wanted is then done in anywell-known way. The signal to disconnect two subscribers lines is sentin automatically bythe one or the other who first hangs up histelephone. By hang in g up the telephone at one of the stationstheground is removed and the line connected with the common line. Thecircuit of the batteryis thus completed from the central office throughsuch other lines of the group as at this moment may be connected withthe common line, and thence through the lines of the two connectedsubscribers to ground. The annunciators of the two lines will thus bethrown down.

The telephone-lines a b 0 cl e are connected normally with the outercommon line, f, and

extend to their respective spring-jacks and to common ground-line g atthe central office.

Anuunciators h i ls l m are provided, as shown, one in each line, at thecentral office.

Line- 6 of station No. 5 is shown connected with the common outer line,f, and with the common line 9 at the central office. If the telephoneweren ow removed from the switch, line ewould be cut ofi" from linef andconnected to ground. See circuits at station No. 3.) The circuit wouldthus be closed to battery through annunciator m, and the shutter ofannunciator m would be thrown down. The central office is thus notifiedof the call, and by inserting a plug in the springjack of the callingsubscriber cuts on his line from the line 9 and connects said line withthe listening operators outfit. The order is then received, and thesubscriber wanted is called'up, and the two are connected in the usualmanner. The spring-jacks of lines a and h are shown thus connected. Thesubscriber who first hangs up his telephone completes a circuit throughthe annunciators in the two connected lines and sends in theclearing-out signal, droppin g the shutters, as indicated by dotted lineat annunciators t k. The circuit thus formed may be traced as follows:From the ground at the central office through the batteryin line g, andby line 0 and such other lines as may be connected at the same time toline f, and thence to line aand through annunciatort', the springjack,and conducting plugs and cord to line b, and through annunciator la insaid line to ground at station No. 2, as shown.

I claim-- 1. A group of subscribers lines normally connected at theirouter ends with a common line, and at the central office with a commonground-line, in which is placed a battery, in combination withannunciators at the central office,onein each line of the group, andswitchin g apparatus at each station, whereby the circuit of saidbattery may be closed to ground at any station, substantially as and forthe purpose specified.

2. Aseries of telephone-lines radiating from a common battery-wirethrough switches and annunciators at the central otfice, (one switch andone annunciator in each line,) and through their several terminalstations to a common outer wire, in combination with switching ap- 5paratus at each station, and means for connecting any two switches atthe central office, whereby the circuit of saicl battery-wire may becompleted through certain lines of the group to the common outer line,and thence throughthecircuitof twoconnected individual xo lines by meansof the switching apparatus at either station of the two individuallines.

CHARLES E. SORIBNER. Vitnesses:

WM. S. GRANGER, GEORGE P. BARTON

